Chapter 3 Ecosystems What Are They and How

Chapter 3 Ecosystems: What Are They and How Do They Work?

Core Case Study: Have You Thanked the Insects Today? • Many plant species depend on insects for pollination and plant reproduction. • Insects can control other pest insects by eating them. • They also mix up the soil Figure 3 -1

Core Case Study: Have You Thanked the Insects Today? • …if all insects disappeared, humanity probably could not last more than a few months [E. O. Wilson, Biodiversity expert]. – Insect’s role in nature is part of the larger biological community in which they live. why are honeybees dis. flv honeybees part 2. flv

THE NATURE OF ECOLOGY • Ecology is – How organisms interact with one another and with their nonliving environment. ( we have to learn about how species interact with their environment, so we can understand how our actions are effecting this delicate balance) Figure 3 -2

So, really intricate and amazing interrelationships occur between plants and animals.

Well, as mentioned earlier, plants rely on insects, birds, and rodents for pollination

And, of course birds and animals need plants……what

Biosphere!!!!!!!

Re-wind: from this diagram I would like you to remember the differences between good and bad ozone, and the greenhouse vs. the ozone layer

What Happens to Solar Energy Reaching the Earth? Solar energy • Warms and lights up the troposphere • Drives the cycling of matter • Evaporates water and drives weather and climate • 1% generates winds • Green plants/algae use less than. 1% in photosynthesis Figure 3 -8

What are the abiotic factors in this diagram? Oxygen (O 2) Sun Producer Carbon dioxide (CO 2) Secondary consumer Primary (fox) consumer (rabbit) Precipitation Falling leaves and twigs Producers Soil decomposers Water Fig. 3 -10, p. 57

Factors That Limit Population Growth • Availability of matter and energy resources can limit the number of organisms in a population. • Examples of limiting factors: (temperature, sunlight, nutrients, dissolved oxygen, salinity…etc) Figure 3 -11

Abundance of organisms Upper limit of tolerance Few No organisms Population size Lower limit of tolerance No Few organisms Zone of intolerance Low Zone of physiological stress Optimum range Temperature Zone of physiological stress Zone of intolerance High Fig. 3 -11, p. 58

Producers: Basic Source of All Food • Most producers capture sunlight to produce carbohydrates by photosynthesis: • KNOW THE FORMULA

Write the chemical equations for photosynthesis and respiration. Explain how these two processes are intertwined; include the terms oxygen, carbon dioxide, light reaction, dark reaction, chloroplasts, mitochondria, photosynthesis, respiration, glucose, water, sunlight, ATP, plants, animals. Good luck!!

Energy Flow in an Ecosystem: Losing Energy in Food Chains and Webs • In accordance with the 2 nd law of thermodynamics, there is a decrease in the amount of energy available to each succeeding organism in a food chain or web.

Energy Flow in an Ecosystem: Losing Energy in Food Chains and Webs • Ecological efficiency: percentage of useable energy transferred as biomass from one trophic level to the next. (240% range) Figure 3 -19

Productivity of Producers: The Rate Is Crucial • Gross primary production (GPP) – Rate at which an ecosystem’s producers convert solar energy into chemical energy as biomass. Figure 3 -20

Gross primary productivity (grams of carbon per square meter) Fig. 3 -20, p. 66

Net Primary Production (NPP) • NPP = GPP – Rate at which producers use photosynthesis to store energy minus the rate at which they use some of this energy through respiration (R). Figure 3 -21

Sun o Ph sis the yn tos Respiration Gross primary production Growth and reproduction Energy lost and unavailable to consumers Net primary production (energy available to consumers) Fig. 3 -21, p. 66

• What are nature’s three most productive and three least productive systems? Figure 3 -22

• Chemosynthesis: – Some organisms such as deep ocean bacteria draw energy from hydrothermal vents and produce carbohydrates from hydrogen sulfide (H 2 S) gas.

Consumers: Eating and Recycling to Survive • Consumers (heterotrophs) get their food by eating or breaking down all or parts of other organisms or their remains. – Herbivores • Primary consumers that eat producers – Carnivores • Secondary consumers eat primary consumers • Third and higher level consumers: carnivores that eat carnivores. – Omnivores • Feed on both plant and animals.

Respond to this statement: An ecosystem could not withstand the absence of producers, but would be fine without consumers.

Decomposers and Detrivores Burying Beetles Video -- National Geographic – Decomposers: Recycle nutrients in ecosystems. – Detrivores: Insects or other scavengers that feed on wastes or dead bodies. Generally scavengers are considered to be larger animals and detrivores are insects. Figure 3 -13

Detrivores Longhorned beetle holes Decomposers Termite and Bark beetle Carpenter carpenter ant engraving galleries ant work Dry rot fungus Time progression Wood reduced to Mushroom powder Powder broken down by decomposers into plant nutrients in soil Fig. 3 -13, p. 61

Aerobic and Anaerobic Respiration: Getting Energy for Survival • Organisms break down carbohydrates and other organic compounds in their cells to obtain the energy they need. • This is usually done through aerobic respiration. – The opposite of photosynthesis

Aerobic and Anaerobic Respiration: Getting Energy for Survival • Anaerobic respiration or fermentation: – Some decomposers get energy by breaking down glucose (or other organic compounds) in the absence of oxygen. – The end products vary based on the chemical reaction: • • Methane gas Ethyl alcohol Acetic acid Hydrogen sulfide

Two Secrets of Survival: Energy Flow and Matter Recycle • An ecosystem survives by a combination of energy flow and matter recycling. Figure 3 -14

Biodiversity Loss and Species Extinction: Remember HIPPO • H for habitat destruction and degradation • I for invasive species • P for pollution • P for human population growth • O for overexploitation

Why Should We Care About Biodiversity? The health of a species reflects the health of an ecosystem which reflects of the health of the biosphere which is where humans live. “We are all connected”

Some species are so critical to the functioning of an Ecosystem that they are called KEYSTONE SPECIES 1800’s sea otters hunted for fur Sea otters eat sea urchins, so with no predators, they began to multiply Sea urchins eat kelp, which then began to disappear Fish begin to decline because Kelp are the breeding grounds for fish, this affected fishermen's catches. California Sea Otter Tax Check-Off - Defenders of Wildlife

Flower power. Rosy periwinkle has given rise to drugs used to treat childhood leukemia and Hodgkin's disease.

Spider find. A compound in the venom of black widow spiders found in the Negev Desert in Israel may hold promise for treating strokes

It had to be yew. The drug Taxol, made from the bark of the Pacific yew, helps fight breast and ovarian cancers.

Food Webs • Trophic levels are interconnected within a more complicated food web. Figure 3 -18

Which of the following ecosystems has the highest average net primary productivity? a. agricultural land b. open ocean c. temperate forest d. swamps and marshes e. lakes and streams Which of the following ecosystems has the lowest level of kilocalories per square meter per year? a. open ocean b. tropical rain forest c. agricultural land d. lakes and streams e. temperate forest

SOIL: A RENEWABLE RESOURCE • Soil is a slowly renewed resource that provides most of the nutrients needed for plant growth and also helps purify water. – Soil formation begins when bedrock is broken down by physical, chemical and biological processes called weathering. • Mature soils, or soils that have developed over a long time arranged in a series of horizontal layers called soil horizons.

SOIL: A RENEWABLE RESOURCE Figure 3 -23

Oak tree Wood sorrel Lords and ladies Fern O horizon Leaf litter Dog violet Grasses and small shrubs Earthworm Millipede Honey fungus Mole Organic debris builds up Rock fragments Moss and lichen A horizon Topsoil B horizon Subsoil Bedrock Immature soil Regolith Young soil Pseudoscorpion Mite Nematode C horizon Parent material Root system Mature soil Red Earth Mite Springtail Actinomycetes Fungus Bacteria Fig. 3 -23, p. 68

Animation: Soil Profile PLAY ANIMATION

Layers in Mature Soils • Infiltration: the downward movement of water through soil. • Leaching: dissolving of minerals and organic matter in upper layers carrying them to lower layers. • The soil type determines the degree of infiltration and leaching.

Soil Profiles of the Principal Terrestrial Soil Types Figure 3 -24

Mosaic of closely packed pebbles, boulders Weak humusmineral mixture Desert Soil (hot, dry climate) Dry, brown to reddish-brown with variable accumulations of clay, calcium and carbonate, and soluble salts Alkaline, dark, and rich in humus Clay, calcium compounds Grassland Soil (semiarid climate) Fig. 3 -24 a, p. 69

Acidic light-colored humus Iron and aluminum compounds mixed with clay Tropical Rain Forest Soil (humid, tropical climate) Fig. 3 -24 b, p. 69

Forest litter leaf mold Humus-mineral mixture Light, grayishbrown, silt loam Dark brown firm clay Deciduous Forest Soil (humid, mild climate) Fig. 3 -24 b, p. 69

Acid litter and humus Light-colored and acidic Humus and iron and aluminum compounds Coniferous Forest Soil (humid, cold climate) Fig. 3 -24 b, p. 69

Leaf mold, a humus-mineral mixture, and silty loam are indicative of a. coniferous forest soil. b. deciduous forest soil. c. tropical forest soil. d. grassland soil. e. desert soil. Soil comprised of litter and humus, and is acidic due to the accumulation of needles a. desert soil b. grassland soil c. tropical rainforest soil d. coniferous forest soil e. deciduous forest soil

Soils found in mid-latitude grasslands would be most accurately described as having a. a high acid content with little organic matter b. a deep layer of humus and decayed plant material c. a layer of permafrost right below the O-horizon d. a high content of iron oxides and very little moisture e. a small amount of nutrients but an abundant decomposer food web

Some Soil Properties • Soils vary in the size of the particles they contain, the amount of space between these particles, and how rapidly water flows through them. http: //techalive. mtu. edu/meec/module 06/Porosity. htm Figure 3 -25

Sand 0. 05– 2 mm diameter Silt 0. 002– 0. 05 mm diameter Water High permeability Clay less than 0. 002 mm Diameter Water Low permeability Fig. 3 -25, p. 70

The porosity of a soil is defined to be the volume of the pores as a percentage of the total volume of soil. Sandy soils have porosities ranging from 30 to 40 percent, compared with 40 to 60 percent for clays. Porosity provides a measure of the amount of water that each soil can retain. Clay soils have a higher porosity and can hold more water. (smaller pores, but more of them)

MATTER CYCLING IN ECOSYSTEMS • Nutrient Cycles: Global Recycling – Global Cycles recycle nutrients through the earth’s air, land, water, and living organisms. – Nutrients are the elements and compounds that organisms need to live, grow, and reproduce. – Biogeochemical cycles move these substances through air, water, soil, rock and living organisms.

The Water Cycle Figure 3 -26

Animation: Hydrologic Cycle PLAY ANIMATION

Water’ Unique Properties • There are strong forces of attraction between molecules of water. • Water exists as a liquid over a wide temperature range. • Liquid water changes temperature slowly. • It takes a large amount of energy for water to evaporate. • Liquid water can dissolve a variety of compounds. • Water expands when it freezes.

Effects of Human Activities on Water Cycle • We alter the water cycle by: – Withdrawing large amounts of freshwater. – Clearing vegetation and eroding soils. – Polluting surface and underground water. – Contributing to climate change.

The Carbon Cycle: Part of Nature’s Thermostat http: //www. epa. gov/climatechange/kids/carbon_cycle_version 2. html Figure 3 -27

Fig. 3 -27, pp. 72 -73

Animation: Carbon Cycle PLAY ANIMATION

Effects of Human Activities on Carbon Cycle • We alter the carbon cycle by adding excess CO 2 to the atmosphere through: – Burning fossil fuels. – Clearing vegetation faster than it is replaced. Figure 3 -28

CO 2 emissions from fossil fuels (billion metric tons of carbon equivalent) High projection Low projection Year Fig. 3 -28, p. 74

The Nitrogen Cycle: Bacteria in Action Figure 3 -29

Gaseous nitrogen (N 2) in atmosphere Food webs on land Nitrogen fixation Fertilizers Uptake by autotrophs Excretion, death, decomposition Ammonia, ammonium in soil Nitrogen-rich wastes, remains in soil Ammonification Loss by leaching Nitrification Uptake by Loss by autotrophs denitrification Nitrate in soil Nitrification Nitrite in soil Loss by leaching Fig. 3 -29, p. 75

Animation: Nitrogen Cycle PLAY ANIMATION

Effects of Human Activities on the Nitrogen Cycle • We alter the nitrogen cycle by: – Adding gases that contribute to acid rain. – Adding nitrous oxide to the atmosphere through farming practices which can warm the atmosphere and deplete ozone. – Contaminating ground water from nitrate ions in inorganic fertilizers. – Releasing nitrogen into the troposphere through deforestation.

Effects of Human Activities on the Nitrogen Cycle • Human activities such as production of fertilizers now fix more nitrogen than all natural sources combined. Figure 3 -30

Global nitrogen (N) fixation (trillion grams) Nitrogen fixation by natural processes Year Fig. 3 -30, p. 76

The Phosphorous Cycle Figure 3 -31

mining excretion Guano Fertilizer agriculture uptake by weathering autotrophs leaching, runoff Dissolved Land Marine Dissolved in Soil Water, Food in Ocean Lakes, Rivers Webs Water death, decomposition weathering sedimentation settling out uplifting over geologic time Rocks Marine Sediments Fig. 3 -31, p. 77

Animation: Phosphorous Cycle PLAY ANIMATION

Effects of Human Activities on the Phosphorous Cycle • We remove large amounts of phosphate from the earth to make fertilizer. • We reduce phosphorous in tropical soils by clearing forests. • We add excess phosphates to aquatic systems from runoff of animal wastes and fertilizers.

The Sulfur Cycle Figure 3 -32

Sulfur trioxide Water Acidic fog and precipitation Sulfuric acid Ammonia Oxygen Sulfur dioxide Ammonium sulfate Hydrogen sulfide Plants Dimethyl sulfide Volcano Industries Animals Ocean Sulfate salts Metallic sulfide deposits Decaying matter Sulfur Hydrogen sulfide Fig. 3 -32, p. 78

Animation: Sulfur Cycle PLAY ANIMATION

Effects of Human Activities on the Sulfur Cycle • We add sulfur dioxide to the atmosphere by: – Burning coal and oil – Refining sulfur containing petroleum. – Convert sulfur-containing metallic ores into free metals such as copper, lead, and zinc releasing sulfur dioxide into the environment. http: //teachers. sduhsd. k 12. ca. us/bbodas/biogeochemical cycleactivity 2007. pdf